Hello! We don't like spam registrations here! All new members will be moderated. User accounts that have been created but not verified through e-mail will be deleted after a week or so. I recommend you fill out fields like "interest" during registration to NOT look like a spammer. You have the option of leaving a phone number.

If you don't have the computer "stopped" it won't do anything. (it needs a functioning processor card to get to a stopped state) Notice that the Normally Open sides of the switch are pulled high. It gets the "low" pull down from the Run/Stop FF IC'H. Look in the top right corner of 880-106.

Hi;
Grant, I would Agree with you that the low for the Switches comes from the Run FF, But, He still shows a SHORT between the two pins. I just checked my board and I don't show ANY short, Both resistors show 1K each and between the pins on the Switch it reads 2K NOT 500 ohms. So when he brings them Low with the processor board in they both go low and output both go high, not one or the other. Without looking at the board I am only guessing what the problem is. I know that I don't have any other ideas !!
Thanks Marty

There was a manufacturing defect in the board and two traces were shorted. A bit of work with an exacto knife and I was able to remove the copper bridge between the traces. I've attached a jpeg of my handiwork.

Now I have a finished Altair. Thanks for sticking with me guys to figure it out.

(Gee --- all I have to show for this, from a demo perspective, is a switch that turns an LED on and off )